Guard-rail assembly with pivotal support posts

ABSTRACT

A guard rail formed of a downwardly open channel whose interior is filled with a bonded-in-place synthetic-resin mass is formed approximately every 10 meters with a downwardly open pocket in which the upper end of a support post is received. A pivot bolt transverse to the rail passes through the rail and the post and allows pivoting of this post relative to the rail in a horizontal plane including the rail. The lower end of the post is received in an upwardly open channel so that on collision of a vehicle with the post or a similar blow being struck to the post below the rail, this post will pivot out of its socket and up into the pocket so that the rail itself will take the blow to prevent a vehicle from flipping over the guard rail.

Glaesenr 11] 3,74,167 [451 Jan. 8, 1974 1 GUARD-RAIL ASSEMBLY WITHPIVOTAL SUPPORT POSTS [75] Inventor: Ernest Glaesener, Dudelange,

Luxembourg [22] Filed: Oct. 11, 1972 [21] Appl. No: 296,653

[30] Foreign Application Priority Data 2,836,476 5/1958 Carter et a1248/439 2,536,760 l/l951 Martin et al. 256/13.l

FOREIGN PATENTS OR APPLICATIONS 99,770 10/1961 Netherlands 52/98 PrimaryExaminer-Jordan Franklin Assistant Examiner-Conrad L. BermanAttorneyl(arl F. Ross [5 7] ABSTRACT A guard rail formed of a downwardly.open channel whose interior isfilled with a bonded-in-placesynthetic-resin mass is formed approximately every 10 meters with adownwardly open pocket in which the upper end of a support post isreceived. A pivot bolt transverse to the rail passes through the railand the post and allows pivoting of this post relative to the rail in ahorizontal plane including the rail. The lower end of the post isreceived in an upwardly open channel so that on collision of a vehiclewith the post or a similar blow being struck to the post below the rail,this post will pivot out of its socket and up into the pocket so thatthe rail itself will take the blow to prevent a vehicle from flippingover the guard rail.

7 Claims, 3 Drawing Figures PATENTEI] JAN 8' 1 GUARD-RAIL ASSEMBLY WITHPIVOTAL. SUPPORT PQSTS CROSS-REFERENCE TO RELATED APPLICATIONS Thisapplication is related to my copending application, Ser. No. 147,817filed 28 May 1971 (now US. Pat. No. 3,704,861 of 5 Dec. 1972) and toapplication Ser. No. 814,054 filed 7 Apr. 1968 (now US. Pat. No.3,603,562).

BACKGROUND THE PRESENT INVENTION In my above-cited application, Ser. No.147,817, I disclose a vehicle barrier or guard-rail structure comprisinga guard rail and posts supporting same, the guard rail being formed of adownwardly open boxshaped channel of thin sheet metal, preferablyunitary (i.e. in one piece) over at least three sides, the interior ofwhich is filled from flank to flank with a foamed or cellularelastomeric synthetic resin bonded to the inner basis of the channel andin force transmitting relationship between the afore-mentioned flanks.Advantageously,.the inner surface of the sheet-metal channel (as well asthe outer surface thereof) is provided with a corrosion-resistantcoating formed by, for example, hot galvanizing (i.e. zinc coating byhot dipping), which has been found to increase the strength of the bondformed between the sheet-metal channel and the synthetic resin. Theguard rails advantageously span lengths between posts far in excess ofthose provided heretofore and at least about 10 meters, the foamedsynthetic-resin filling (apparent density of 30 to 80 kg/m within thechannel serving to provide the requisite stiffn'ess and self-supportingcharacter. In other words, whereas the sheet-metal channel is composedof such thin sheet metal as to preclude self-supporting spans of 10meters or more, the presence of the foam body, bonded to all of theinternal surfaces of the channel and filling the latter, stiffens theguard rail without significantly increasing the tendency of vehicles torebound therefrom and sufficiently to span such distances. Moreover, thechannel is preferably nonclosed, i.e. free from any rigid forcetransmitting member between the flanks and the free ends thereof. Thisis not to say that a sheet-metal enclosure member cannot be provided atthe open end of the channel where the closure member does not act ininward forcetransmitting relationship between the flanks of the channel.Consequently, the' channel appears to have an open end and permits thesynthetic-resin filler to transmit all force between the flanks of thechannel.

According to a more specific feature of the inventon disclosed in myprior application, the cellular elastomer entirely fills the channelwhose lateral walls lie at right angles to a planar top surface, theelastomer filling being flush with the mouth of the channel. Theelastomer is preferably a stiff or hard polyurethane foam of theclosed-cell type which is formed in situ within the channel and thusbonds effectively to all of the interior surfaces thereof. Duringmanufacture of the guard rail, pockets or openings may be left in thepolyurethane foam filling to receive the support posts which aredesigned to resist torsion and preferably are generally flat with abroad surface oriented parallel to the guard rail. In other words, thebending resistance of the support post is greater in the longitudinaldirection (of the guard rail) than in the transverse direction thereof.To

provide a suitable mounting of the guard rail upon the post, it has beenfound to be advantageous to dimension the interior of the socket orpocket in which it is received to be larger than the external dimensionsof the posts received therein. A torsion-free mounting of the guard railupon the post can be realized by lining the pocket with sheet metalwhich is bonded (during manufacture of the guard rail) to thepolyurethane foam mass and may be secured to the post by an adhesive,preferably an elastic adhesive such as polyurethane.

Where the sheet metal of the channel is extremely thin (preferably of athickness of 2mm), the guard rail filled with the polyurethane-foam isfound to be light compared to equal lengths of conventional guard rails.However, the bonding of the polyurethane foam to all of the interiorsurfaces provides resistance to torsion and bending within the guardrail and enables the latter to span distances of, say, 10 to 20 metersbetween support posts, some 4 to 6 times greater distances than theconventional post spacing. Furthermore, the mounting of the guard railupon the posts, the manufacture of post and guard rail, and the low costof both the guard rail and the posts represent major advantages.

A further advantage of the system of application, Ser. No. 147,817 canbe found in the manner in which the' guard rail absorbs the energy ofimpact of heavy vehicles, such as trucks. Heretofore, a collisionbetween the truck and the roadside barrier has resulted in breakage ofthe barrier unless the latter was dimensioned to resist such breakage.In these cases, a large number of posts were provided to distribute theforce of the collision and, where resistance to impact was high, therewas always the danger that the truck would roll over or jump thebarrier. Not only was this a disadvantage, but a close spacing of thesupports invariably increased the cost of the barrier many times. Thesystem of the present invention provides a crushable rail designed totake up the energy of impact and limit rolling-over or rebound at lowcost. Unless the force of collision is sufficient to break the barrier,the usual permanent distortion of the guard rail is avoided in the caseof the present system because of the self-restoring quality of a fillingbonded to the sheet-metal walls.

The barrier of my prior invention, although composed of metal sheet aspreviously'described, is characterized by a membrane-like engagementwith the vehicle. Hence, a vehicle colliding with the barrier willdeflect the latter into an S-curve or undulation which will ride alongthe barrier together with the vehicle, thereby precluding rebounding ofthe latter onto the roadway. The barrier may have the vehicle-guidesurface located significantly above the height of present barriers and,consequently, a barrier height of 70cm has been found to beadvantageous. This height is capable of preventing rollover of heavyvehicles.

channel is provided to reduce corrosive attack. With closed-cell foams,as described earlier, moisture penetration into the channel isprecluded, even when the designed to receive the plug end of alongitudinally contiguous guard rail. When the two guard rail lengthsare joined in this manner, the surface exposed to the vehicles issubstantially continuous. Alternatively, the junction between two guardrails may be formed by providing a connecting socket arrangement ofsteel sheet which covers the upper surface and walls of each channel andis bonded thereto with an adhesive. The junction may also be filled withan elastomeric material, e.g. .a foam polyurethane, capable of bondingto the zinc-coated sheet-metal surfaces. This filler maintains thecorrosion resistance, strength and impactcharacteristics of the raileven at the junctions.

I A common problem with guard rails, even to a cer-- tain extent withthose of my prior applications, is that the post presents a danger to amotor vehicle colliding with the rail. Particularly in locations wherethe rail is arranged at a height of 700750 mm rather than the customaryheight of 550600 mm is it a common occurrence that a vehicle strikingthe guard rail catches on a post and flips over into the opposing laneof traffic.

An attempt has been made to cure this difficulty by means of break-awayposts which fracture easily when the corresponding rail section isstruck. Such an arrangement has a limited degree of efficacity since thenecessary fragile posts often snap due to normal tensions caused byexpansions and contractions resulting from changes in temperature, or,alternatively, they are made so strong that they do not break when theyare supposed to.

OBJECTS OF THE PRESENT INVENTION It is therefore an object of thepresent invention to provide an improved guard-rail assembly for aroadway.

A more specific object is the provision of such an assembly whosesupport posts present no danger to vehicles colliding with the rail.

SUMMARY OF THE INVENTION I attain these objects in a guard-rail assemblyof the above-described general type wherein the post is pivoted at itsupper end to the rail and is received at its lower end in the ground ina socket in the form of a channel extending parallel to the rail. Insuch a system a vehicle coming into contact with the post will merelyswing the post out of its socket about a pivot axis transverse to therail, with the post pivoting in a horizontal plane including the guardrail. Thus the post, while serving to support the rail adequately,offers little resistance to a blow substantially parallel to the rail sothat the rail itself absorbs the shock, as is intended with my guardrail.

According to other features of my present invention the rail is formedgenerally as described in my prior applications, with a pair of centrallongitudinally extending grooves on its sides. The pivot extends throughthe center of the rail at these grooves, midway in its height.

Also-thepocket receiving the upper end of the post is made of sufficientlongitudinal length to receive the post should it be pivoted to ahorizontal position.

DESCRIPTION OF THE DRAWING The above and other objects, features, andadvantages will become apparent from the following, reference being madeto the accompanying drawing in which:

FIG. 1 is a side sectional view of the assembly according to the presentinvention;

FIG. 2 is a section along line IIII of FIG. 1; and

FIG. 3 is a vertical section through an alternative embodiment of thepost socket SPECIFIC DESCRIPTION In FIG. 1 I have shown a guard-railstructure comprising a three-sided channel 10 of sheet metal, preferablysteel, which is comated on its internal surface and external surfacewith corrosion-resistant layers. Preferably the channel 10 ishot-galvanized, i.e. coated with zinc internally and externally byhot-dipping. Prior to galvanizing the sheet metal has a thicknessbetween 0.2mm and 2.5mm, here about 1.2mm. The channel 10 is generallybox-shaped, i.e. provided with an upper wall 12 and a pair of parallelflanks 14 and 15 lying at right angles tothe upper wall 12. This upperwall 12 is planar and horizontal whereas the flanks 14 and 15 areprofiled or corrugated, as described in the aforementioned applications.More specifically a generally trapezoidal recess or groove 16 is formedin the center of each of the flanks 14 and 15 and extends the fulllongitudinal length of each rail 10. In addition each flank 14, 15 goesover into the top 12 and bottom 13 of the channel 10 by means of anangled region 17.

The channel 10 has a length of 10-20 meters, usually about 16 meters.The interior of the channel is filled completely with a foamed syntheticresin, preferably a closed-cell compression-resistant polyurethane foamwhich is foamed and cured in situ within the channel and in contact withthe galvanized walls of the sheetmetal channel. Surprisingly, such afirm bond is formed between the foam filling 18 and the galvanized wallsthat the foam not only acts as a packing for the transfer of transverseforces between the parallel walls of the channel 10, but also as abending resistance for the rail structure as a whole. More specifically,the elimination of any slip or relative movement between the foamrubberbody and the walls of the channel at the interface between themrigidifies the structure and increases its bending moment so that, inspite of the small thickness of the sheet metal, the guard rail isself-supporting. This surprising result is underlined by the fact thatrubber surfaces generally have not been bonded successfully heretoforeto galvanized sheet metal.

While the modulus of elasticity, resistance, compression, strength,density and apparent density of the foam will be established inaccordance with the desired resistance to bending and strength of theguard rail and, therefore, in accordance with the transverse dimensionsof the box-like rail structure, it has been found that certainparameters should be observed. Preferably, the transverse width of therail should be about 300mm while its height is about 500mm. When such asystem is used as a medium separator between two lanes of oppositelymoving traffic, it is desirable as mentioned above to employ a channelhaving a sheet metal thickness of 1.2mm and a polyurethane hard foamwith an apparent density of 50 kg/m. The polyurethane foam is producedby casting, immediately after formation, a mixture of ,41 percentpolyester resin containing alcoholic or hydroxylic functional groups,,53 percent of a di-isocyanate and about 6 percent of a fluorinatedhydrocarbon such as that marketed under the name FREON or FRIGAN. Sincethe art describes many polyurethane foam compositions of similarhardness,

substantially any of these can be substituted, provided thatapproximately equivalent compressive characteristics are obtained. Infact, practically any of the dior polyisocyanates hitherto used for theproduction of polyurethane foam and practically any of thepolyfunctional alcohols which have been provided in connectherewith, maybe used in accordance with the present invention as well. I prefer touse the foam designated commercially as MOLTOPREN.

The advantages of such a system are manifold. For example, thepolyurethane-foam filling 18 transfers force from one flank of the railto the other with some dissipation and absorption of energy, althoughthe overall configuration need not be significantly distorted. As aconsequence, the composite body retains its strength during impact of avehicle therewith and the vehicle encounters a guard rail withsignificantly greater strength than guard rails of thicker sheet metal.The rebounding effect is nil. The system need not be used with strongposts..Finally, kinking of the guard-rail structure is avoided since themass within the guard rail resists local penetration, and endeavours tore-establish its original configuration immediately upon release of anyapplied force.

It has been already been pointed out that the bottom 13 channel 10 canremain open. By this I mean that no special measures arerequired toclose the mouth of the channel to gain additional strength. For example,I may provide the lower ends of the walls 14 and 15 with inwardlyextending flanges or lips, 14a and 15aadapted to underlie the body offoam polyurethane within the channel. Alternatively, I may taper thewalls 14 and 15 downwardly and inwardly to provide a narrow slot throughwhich the post may be inserted. Also it is possible to cover the mouthof the channel with a plate which may bridge the two walls, but need notbe disposed in force-transmitting relationship between'them insofar asinward forces are concerned. The closed-cell polyurethane foam utilizedin accordance with the present invention has the advantage that it isimpenetrable to moisture. The body.18 of foam polyurethane thus sealsthe interior of the channel against corrosion resulting from contactwith moisture, constitutes a weather-resistant filler and providesstructural support for the thin sheet-metal walls. Since the guard railsof the present invention can span exceptionally long distances, they areable to follow bends in the roads more successfully and to be deformedin accordance with road curvatures without special machinery orpreparation.

The polyurethane foam is polymerized and cured within the channel at thetime of its manufacture and any conventional method of moldingpolyurethane may be used to this end. Generally the components are mixedtogether and poured or injected into the channel while the latter isheld in an inverted, upwardly open state, the ends of the channel beingprovided with walls of any desired configuration. Y

A smooth surface for the eventual underside of the guard rail and forthe upper surface at the time the guard rail is produced by the use of astrike board or by providing a temporary cover for the channel mouth.The cover is coated with a parting material to which the polyurethanefoam is not adherent.

The recesses or corrugations 16 formed in the sidewalls 14 and 150i thechannel increase the resistance to compression on collision with thevehicle and also form guides restricting the tendency of an impactingvehicle to ride up along the rail. After forming and galvanization, thechannel is advantageously degreased prior to the casting of the formingmixture therein. In some cases it has been found to be advantageous toapply awash-primer or some other bonding coating, preferably of thevolatile'solvent type, to increase adhesion between the foampolyurethane and the walls of the channel. A suitable primer is thesolvent containing adhesive EC 1357 marketed by the 3M Company.

The rail 10 is provided with a downwardly open sheet metal pocket Illhaving planar end walls 11a, side walls 11b, and a top wall He, thislast-named wall being adhesively fixed to the top wall 12 of the channel10. Thus the pocket 1 1 has the shape of a downwardly open rectangularbox of a transverse width equal to the space between the lips 14a and15a of the flanks l4 and 15. In case no such lips 14a and 15a areprovided, the sides 1112 are also adhesively attached to the insides ofthe flanks 14 and 15 at the groove 16. The area between the side walls11b and the flanks l4 and 15 is filled with a much more dense foam body19 of the above described general type but having a density of about 250kg/m. This filling is formed as described above, and serves to impartthe same rigidity to the rail in the region of the pocket as elsewherealong its length.

The rails 10 are formed so that they can be fitted together end-to-end.This is achieved by forming one end with a recess by eliminating thefoam filling for about 500mm. The other end is correspondingly formed ofreduced cross sectional size to fit exactly into such an empty end.

Posts 20 support the rails 10 at a height of 650mm-750mm from the groundlevel G. Each post is made of a steel shell 23 of closed rectangularsection filled like the channel 10 with a polyurethane mass 22. A round,oval, or variously polygonal post 20 is also usable equally well. Theupper end region of the post 20 is thickerthan the lower region and isreceived with slight'clearance in the pocket 11. The very upper end 24of the post 20 and the lower end 25 are rounded and the end 24 engagesthe top wall of the pocket 11.

A bolt 21 orthogonal to the longitudinal direction of the rail 10 andpassing completely through it at the base of the grooves 16, thereforemidway up its height, also passes through a corresponding hole in thepost 20 so that this post may pivot about an axis A defined by this bolt21. The dot-dash line position shown in FIG. 1 shows how the length L ofthe post, here 750mm from its end 25 to the pivot 21 is slightly lessthan half-the longitudinal length of the pocket 11, so that this postcan swing up entirely into the pocket 11. As a matter of fact the postscan be attached to the rails at the factory and shipped in in thisswung-up position. The pocket has an overall length of at least 1,000mmas will be described below.

The lower end 25 of the post is received in a socket generallydesignated 30 made of cast iron or steel and mounted on a fixed base 31of, for example, concrete. The socket 30 is a channel having flanks 32and 33 which extend upwardly and parallel to each other and to the rail10, only confining movement of the end transverse to the rail 10. Thusthe only obstacle to swinging of the post 20 about its axis A iswhatever dirt or sand lies to either of the open ends of the channel 30.Indeed the slight resistance of such dirt, since the end 25 is only100mm 200mm below ground level G, is advantageous in that it preventsthe post from pivoting except when such pivoting is strictly necessary.The channel may be coated with, for example, synthetic resin in order toprevent the post end from rusting fast to it. The lower end portion ofthe post 20 is smaller in cross-section than the upper portion so thatif the post 20 is pushed slightly to the side, it is still able to swingup into the pocket 11. It is possible to taper the post 20 graduallyrather than just step it to make the lower region slimmer.

The arrangement shown in FIGS. 1 and 2 is intended to be used betweenopposite lanes of traffic. To this end the pocket has a length of 2L andthe channel 30 is open on both ends. In the case of the assembly beingused at the outside edge of a highway, where it is only likely to be hitby cars in one direction, it is only necessary to have the channel 30open on one end and it is only necessary that the pocket 11 be extendedwidely to one side of the pivot 21 since the post 20 is only likely tobe pushed in this direction. Thus, the pocket 11 can end at one end atthe location shown in FIG. 1 by dot-dash line B and the correspondingend of the channel 30 can be closed, as shown at 35 in FIG. 3.

As shown in FIG. 1 the base 34 of the channel 30 is upwardly concave andhas the same radius of curvature, equal to L, as the lower end of thepost 20. FIG. 3 shows a channel 30' whose base 34 is planar. Thus when avehicle strikes the guard rail with a sufficient component of forceparallel to the rail 10, the post 20 will simply swing up, pivotingabout the axis A. In this manner the rail itself will act to absorb theenergy of the impact, as described at length in my prior applications,so that rather than rebounding or going over the rail, the vehicle willbe brought to a stop at the edge of the roadway.

I claim:

1. A guard-rail assembly comprising:

a horizontal rail formed with at least one downwardly open pocketelongated in the longitudinal direction of said rail;

a vertical post having an upper end received in said pocket;

a pivot between said upper end and said rail and defining for said postrelative to said rail a pivot axis extending transverse to thelongitudinal direction of said rail; and

an upwardly open socket in the ground receiving the lower end of saidpost, said socket being an upwardly open channel extending parallel tothe longitudinal direction of said rail, said post being pivotal aboutsaid axis to swing said lower end upwardly free from said channel insaid direction.

2. The assembly defined in claim 1 wherein said pocket is sufficientlyelongated in the longitudinal direction of said rail that said post maypivot about said axis into a position parallel to said rail.

3. The assembly defined in claim 1 wherein said axis is spaced from thetop edge and from the bottom edge of said rail. v

4. The assembly defined in claim 3 wherein said rail is formed on bothsides with a groove, said axis'passing through said grooves.

5. The assembly defined in claim 1 wherein said rail is formed of adownwardly open sheet metal shell, a downwardly open sheet metal liningdefining said pocket, and a synthetic-resin mass substantially fillingsaid shell and adhering to the interior of said shell and the exteriorof said lining.

6. The assembly defined in claim 1 wherein said chennel has a pair ofupwardly extending flanks laterally embracing said lower end.

7. The assembly defined in claim 6 wherein said flanks are between mmand 200 mm in height and have upper edges substantially flush with theground level.

1. A guard-rail assembly comprising: a horizontal rail formed with atleast one downwardly open pocket elongated in the longitudinal directionof said rail; a vertical post having an upper end received in saidpocket; a pivot between said upper end and said rail and defining forsaid post relative to said rail a pivot axis extending transverse to thelongitudinal direction of said rail; and an upwardly open socket in theground receiving the lower end of said post, said socket being anupwardly open channel extending parallel to the longitudinal directionof said rail, said post being pivotal about said axis to swing saidlower end upwardly free from said channel in said direction.
 2. Theassembly defined in claim 1 wherein said pocket is sufficientlyelongated in the longitudinal direction of said rail that said post maypivot about said axis into a position parallel to said rail.
 3. Theassembly defined in claim 1 wherein said axis is spaced from the topedge and from the bottom edge of said rail.
 4. The assembly defined inclaim 3 wherein said rail is formed on both sides with a groove, saidaxis passing through said grooves.
 5. The assembly defined in claim 1wherein said rail is formed of a downwardly open sheet metal shell, adownwardly open sheet metal lining defining said pocket, and asynthetic-resin mass substantially filling said shell and adhering tothe interior of said shell and the exterior of said lining.
 6. Theassembly defined in claim 1 wherein said chennel has a pair of upwardlyextending flanks laterally embracing said lower end.
 7. The assemblydefined in claim 6 wherein said flanks are between 100 mm and 200 mm inheight and have upper edges substantially flush with the ground level.